The present invention relates to an apparatus for mixing and preparing fluid materials, in particular mold sand, with a cylindrical mixing vessel.
Mixers are known in which centrifugal shafts and mixing arms are provided; however, the shafts and mixing arms do not revolve but are fixedly arranged. In these known mixers, in order to feed the material to be mixed to the mixing tools either the mixer base is set in rotation, which entails considerable problems in sealing the rotating mixer base against the stationary mixer wall, or the entire mixer vessel is set in rotation with a fixed arrangement of the mixing tools. See for example DE-A-33 12 869 Al. Both these arrangements require a complicated and fault-prone construction as far as the discharge door and the sealing of the mixing upper part with respect to the rotating mixing vessel are concerned.
It is the principle object of the present invention to avoid the above disadvantages and provide a mixer which is simple in construction, inexpensive to produce and presents no problems in operation.
Further objects and advantages will appear hereinbelow.